There is little evidence that immigrants in the country illegally are trying to register to vote

Arizona, which has become infamous for its hostility toward immigrants who are in the country illegally, lost an important case in the U.S. Supreme Court last year when the justices ruled that the state couldn't require proof of U.S. citizenship as part of the registration process for voting in elections for Congress. The 7-2 decision said that, where federal elections were concerned, the state had to "accept and use" a federal registration form on which an applicant states under penalty of perjury that he or she is a citizen without having to provide a passport or other documentation.

The decision was good policy as well as good law because there is little evidence that immigrants who are in the country illegally are trying to register to vote in meaningful numbers. On the other hand, a requirement to supply documentation could keep many citizens — immigrants and otherwise — from exercising the franchise. Like efforts to require a photo ID at polling places, a requirement of proof of citizenship disproportionately affects minorities and the poor.

Unfortunately, despite its loss in the Supreme Court, Arizona is seeking another bite at the judicial apple. It has joined the state of Kansas in a lawsuit seeking to force the U.S. Election Assistance Commission to include in the federal form given to Kansas and Arizona voters instructions that they provide proof of citizenship. A federal district judge in Kansas ruled for the states, and this week the U.S. 10th Circuit Court of Appeals in Denver heard an appeal by the U.S. government.

If you don't recognize the name "Election Assistance Commission," you aren't alone. It's an obscure four-member body that has been charged by Congress with enforcing provisions of the National Voter Registration Act of 1993 — also known as the Motor Voter Law — that allows citizens to register to vote when they apply for or renew a driver's license, or by mailing in a simple form. Under the law, the commission, "in consultation with the chief election officers of the states, shall develop a mail voter registration application form for elections for federal office." In practice, that means that the commission can customize the form to include "state-specific" information.

When Arizona tried to get the commission to include a proof-of-citizenship requirement in its state-specific instructions, the panel deadlocked 2 to 2. It would be impossible for the panel to act on such a request now because all four seats (believe it or not) are vacant. But a federal district judge agreed with Kansas and Arizona that the commission staff was not only able but required to update the federal form to "reflect each state's laws."

Congress, which has the power under the Constitution to override state rules for congressional elections, clearly intended to make voting easier, not harder.

The 10th Circuit Court could conceivably rule against Kansas and Arizona on the grounds that only the commission itself can add the language they seek. But there is a more important reason for the states to lose: Congress, which has the power under the Constitution to override state rules for congressional elections, clearly intended to make voting easier, not harder. The appeals court should recognize that that intention trumps the two states' desire to make citizens show their papers.